Letoff mechanism for looms



April 1, 1953 o. -v. PAYNE. 2,335,646

LETOFF MECHANISM FOR LOOMS.

Filed July 25, 1951 3 ShFS-Sheet 1 FIG.I

INVENTOR OSCAR V. PAYNE ATTORNEY o. v-. PAYNE LETOFF MECHANISM FOR LOOMS April 21,1953

:5 Sheets-Sheet 2 Filed July 25, 1951 INVENTOR OSCAR V. PAYNE ATTORNEY.

April 21, 1953 o. v. PAYNE 2,635,646

LETOFF MECHANISM FOR LOOMS Filed July 25, 195i s Sheets-Sheet a 7 FlG.9 FIG."

FIG.I4

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ATTORNEY Patented Apr. 21, 1953 7 2,635,646 LETOFF MECHANISM FOR LOOMS Oscar V. Payne, Leicester, Mass., assignor to Y Crompton & Knowles Loom Works, Worcester,

Mass., a corporation of Massachusetts Application July 25, 1951, Serial No. 238,407

' 9 Claims.

This invention relates to improvements in letoff mechanisms for looms and it is the general object of the invention to provide a letoff mechanism so constructed as to provide uniform delivery of warp from the warp beam for the weaving process.

In the type of letofi mechanism to which the invention moreparticularly relates there isemployed a worm gear secured to 'a warp beam and meshing with a worm carried by a weighted carrierwhich cooperates with the worm and worm gear to tend to turn the warp beam backwardly for the purpose of tensioning the warp. -Asthe warp is consumed the carrier, turns forwardly with the warp beam until a regularly moving lever or similar part on the loom moves an actuator rack which effects turning of the Worm for the purpose of allowing the weighted carrier to .move backwardly with respect to the warp beam. v

In the past it has been customary to make a letoif of this type with a clutch having two parts i one of which is turned by the actuator and the other of which isfixed with respect to the shaft to which the worm is secured, and the clutch parts have been so made as to require longitudinal motion of one of the parts along the shaft in order to establish a new holding relation with respect to the other part. Under some conditions letofi mechanisms of this type are observed to keep the warp beam and the weighted carrier in the same relative position with respect to each other for a number of picks and .then the clutch parts cooperate to turn the worm to effect a sudden and relatively large backward feeding of the weighted carrier with respect to the warp beam, thereby subjecting the latter to forces which exert abnormal strains on the warp threads to create a sudden increase in their tension.

It is anfimportant object of the present in-' vention to provide a letofi" mechanism of the general type already described wherein the clutch parts are not required to move longitudinally of the worm shaft and are so constructed that the slightest motion of one of the clutch parts by the actuator will be transmitted to the worm shaft to 'eifect. backward motion of the weighted carrier relative to the warp beam. In practice it is found that a letoff formed according to'thepresent invention acts with great regularity 'and effects only slight relative changes between the weighted carrier and the warp beam whichdo not subjectthe latter toobjectionable momentary increasesv in the forces acting, on it.

'It is'a further object of the invention to provide primary and secondary clutches intermediate the actuator and the worm shaft, the primary 1 clutch having direct driving relation with the shaft and the secondary clutch being moved by the actuator and including a driven clutch member common to the primary and secondary clutches.

stroke of the actuator.

to the worm gear to which it was moved on the feeding stroke of the secondary clutch part.

The actuator derives its'working stroke positively from the loom and is given its return stroke by a spring. The previously mentioned rollers are held in force transmitting position by resilient means which however are collec--' tively weaker than the spring which gives the actuator its return stroke so that the spring can overcome the resilient means of the several rollers to move them slightly away from transmitting position.

It is a still further object of the invention to provide a drive unit for a letofif including the I previously mentioned rollers and having a part adapted for cooperation with the actuator and having another part to be driven by the rollers and provided with a clutch element to drive the worm shaft.

In order that the invention may be clearly" understood reference is made to the accompanying drawings which illustrate by way of example three embodiments of the invention and f in which:

Fig. 1 is a side elevation of part of a loom' having the preferred form of the invention ap-' plied thereto,

Fig. 2 is an enlarged side elevation of part of the structure shown in Fig. 1, parts being removed,

Figs. 3, 4 and 5 are enlarged horizontal sections on lines 3--3, 4-4 and 5-5, respectively,

Fig. 2,

Fig. 6 is a vertical section on line 66, Fig. 4,

Fig. 7 is a transverse section through the worm shaft showing the clutch element thereon,

Fig. 8 is a side elevation looking in the direction of arrow 8, Fig. 7, Y Fig. 9 is a view similar to a part of Fig. 2

force but showing the modified form of the invention,

Fig. 10 is a horizontal section on line 10-40, Fig. 9,

Fig. 11 is a vertical section on line Hli, Fig. 9,

Fig. 12 is a fragmentary plan view looking in the direction of arrow I2, Fig. 11, parts being removed, to show the relation between two of the driving rollers and associated parts,

Fig. 13 is a side elevation of the driven clutch member common to the primary and secondary clutches and looking in the direction of arrow I3, Fig. 12,

Fig. 14 is a view similar to Fig. 12 showing the second modification,

Fig. 15 is a view looking in the. direction of arrow l5, Fig. 14, and

Fig. 16 is a perspective view of one of the spring holders shown in Fig; 14.

Referring particularly to Fig. 1, the loom frame I' supports harness frames 2 which provide warp sheds W l and W2 in the warp W which is fed forwardly or to the right as viewed in Fig. 1 from the warp beam B. The latter has .a shaft 3 mounted for rotation about a horizontal axis and for this purpose the loom is provided at the rear end thereof with bearings one of which is shown at 4. Secured to the warp beam is a worm gear concentric with and turning in unison with the beam. Rotatable about the shaft 3 of the warp beam is a weighted carrier '1 the rear part of which is provided with a segment 8 for a rope or cable 9 the lower end of which has attached thereto a weight not shown herein but tending to move the carrier backwardly or in a counterclockwise direction as viewed in Fig. 2.

The carrier has rotatable therein a shaft ill to which a worm I l meshing with the worm gear is keyed at [2. The carrier is hollow and has. a part It which exerts an upward force on a ball bearing l4 engaging the lower end of the worm. Normally, the warp beam, worm and worm gear will be locked to the carrier so lon as the angular relation of the worm remains unchanged with respect to the worm gear.

The crank shaft [5 of the loom rotates each beat of the loom to reciprocate the lay l6 backwardly and forwardly and has mounted thereon an eccentric I! to drive an eccentric rod [8 extending rearwardly and connected to a lever l9 pivoted on a stationary part of the loom, such for instance as the bearing 4. The lever 19 has an arm or wing 20 which rocks in a horizontal plane and moves substantiall parallel to the axis of the warp beam due to rotation of the crank shaft [5.

The carrier has slidably mounted therein an actuator rack 25 having a head 26 which will be engaged by the wing 20 when the carrier turns to a position to advance the head within the range of motion of the wing. A compression spring 21 fits into the actuator 25 and has one end thereof engaged with the carrier and acts in opposition to the wing 20. When the latter moves toward the warp beam and engages head 26 the actuator will be given a positive horizontal working stroke derived from the loom, upward as viewed in Fig. 4, and when the wing 20 swings away from the warp beam the spring 21 will give the actuator a return stroke. As will be set forth hereinafter the reciprocation of the actuator, one side of which is formed with rack teeth 28, is utilized to turn the shaft H3. The latter has a hand wheel 29 secured to the upper part thereof for manual turning of the worm independently of the actuator.

In carrying the preferred form of the invention into effect a primary clutch element 35 is keyed at 36 to shaft in and has upwardly facing clutch teeth 31 formed as shown in Figs. 7 and 8. As weaving continues the beam and worm gear as well as the carrier turn clockwise, Fig. 2, or forwardly, and when clutch element 35 is turned in a clockwise direction as viewed in Fig. 7 the worm l I will turn to effect counter-clockwise or backward angular motion of the carrier 7 as viewed in Fig. 2.

Surrounding the shaft H1 is a driven or intermediate clutch member 40 which as shown in Fig. 4 has four flat surfaces 41 substantially parallel to the axis of shaft H]. The lower part of the. member 40 has a second primary clutch element 42 secured thereto as by screws 43, see Fig. 5, to engage and have driving relation with the first primary clutch element when the member 49 is in its normal low position.

A secondary shell-like driving clutch element 45 is concentric with shaft i5 and surrounds the greater part of inner driven member and has a cylindrical internal surface 46 the lower part of which turns on the lower cylindrical part. 41 of the member 413. The secondary element has gear teeth 48 integral therewith meshing with the actuator rack 25, whereby the secondary element is oscillated about the axis of shaft l0 incident to loom operation. These teeth are of sufficient length to permit sliding of. the secondary element longitudinally of the shaft while still remaining meshed with the rack, as will be described hereinafter.

The fiat surfaces 4| and the cylindrical surface 46 form wedge shaped pockets 5!] the lower ends of which are defined by horizontal shoulders 5| on the member 49. Located in each pocket 50 is a force transmitting roller 52 extending substantially parallel to the axis of shaft in and held normally in force transmitting relation between the driving secondary element 45 and the driven member 49. by resilient means, such as a small leaf spring 53. The shoulder of each pocket limits downward motion of the associated roller and spring, and a wall 54 on member 40 for each pocket backs up the associated spring 53.

Fitted across the top of the secondary element 45 is a retainer disk 55 which fits against the upper end of the driven member 40 and extends over the pockets and serves to limit upward motion of the rollers and their springs. This disk is. normally held in down position by a compression spring 56. located between a collar 51 secured to shaft 10 and a washer 58 overlying, the disk. The downward force of spring 56 is exerted against the driving member 40 but preferably not against the shell-like driving secondary element 45,. leaving the latter free to respond to the action of the previously mentioned spring 2'1.

In the operation of the form of the invention thus far described the wing 20 and spring 2'! will eifect reciprocation of the actuator 25 each time the carrier isin such position that the head 26 can be engaged by the wing. When the head is pushed by the wing the actuator rack by its engagement with teeth 48 will give the secondary driving clutch element a feeding motion in a clockwise direction as viewed in Fig. 4, and this held in. driving position by. their springs'53. This turning: of the member 40 will be communicated through the primary clutch elements to the shaft I and the worm I I to effect turning of the carrier in abackward direction relative to the warp beam. The gear teeth 48 may be considered as operative connection means between the actuator rack and the element 45.

After the wing 20 has completed its working stroke and starts away from the warp beam the spring 21 will give the actuator a return stroke and the actuator acting through the teeth 48 .will' give the element 45 a return motion in a counter-clockwise direction, Fig. 4. During this latter turning of the element 45 the rollers would :be moved a slight distance toward the wider ends of the Wedge shaped pockets against the action of their springs 53. The spring 21 is strong enough, however, to overcome the combined resistances of thesprings 53 as they oppose motion of the. rollers out of driving relation between member 40 and element 4 5 due to return motion of the element 45. As soon as the spring 21 has returned the actuator to its normal position shown in Fig. 4 the resilient means 53 will move their rollers toward the narrower ends of the pockets and reestablish driving relation between the surfaces 4| and 46. I

During this operation the driven member 40 does not have a longitudinal motion with respect to the, shaft I0, the secondary shell drivingelement 45 and the driven member 40 remaining at the same location along the length of the shaft for both the feeding and return motions of the element 45. If it should be desired to disconnect the shaft I0 from the member 40 the disk 55 can be engaged by the operator's fingers and lifted against the action of spring 56 to slide member 40 from its normal down operative position to its raised inoperative position to disconnect the two primary clutch elements. When 7 the member40 is in its inoperative raised posi tion it is rotatable relatively to shaft I0, and I the worm II can then be turned in the desired position, as in the event of a pickout, independently of member 40, after which the disk is released and the spring 56 returns the clutch elenients 35 and to their normal driving engagement. This engagement remains uninterrupted 5 throughout the rotation of shaft I0 so long as the driven member 40 is in its normal down positi en shown in Fig. 2.

In the modified form of the invention much of the matter thus far described will be utilized but a different form of clutch is utilized. It is tobe understood that the preferred formalready described is more readily adaptable for useon existing letoff mechanisms made according to my prior Patent No. 1,803,143, whereas the modified form of the invention may be used'for installation .on new looms.

Referring particularly toiFigs. 9-13, the shaft I10 corresponds to shaft I0 and has secured therete primary clutch element II held tothe shaft has gear teeth 83 to mesh with the rack actuator and has an internal cylindrical surface 84 the lower end of which fits a cylindrical surface 85 on the lower part of the member 15. The latter member is provided with a groove 86 into which fits a lock or positioning ring 81 on which the under side of the element 82 rests.

The upper part of the member I5 extends somewhat above the top of the element 82 and has each'corner thereof provided with notches 90 to receive a second lock or positioning ring 9|.

Below this ring is a disk 92 which extends beyond the upper periphery of the clutch element 82 .with reference to the axis of shaft 10 to provide a hand hold.

The cylindrical surface 84 forms with the flat surfaces 80 a plurality of pockets 95 in each of which is located a force transmitting roller 95. These pockets are wedge shaped somewhat as described in connection with the preferred form of the invention and each roller is associated with a resilient means such as a leaf spring 97 urging the associated roll toward the narrow end of the corresponding pocket. Each spring may be hung on pins 98 extending from the corre-, sponding flat surface 00, as indicated for instance in Fig. 13. The rollers and their resilient means 91 are confined in their pockets by the overhanging disk 02 and the latter is held against upward motion relative to the member 15 by the lock ring 9|. The secondary element 82 is therefore held between the ring 81 and the disk 92 both of which are positioned by the member I5 and,

this latter member and the element 82 are thus formed as a unit.

A spring I 00 similar to spring 56 exerts a downward force on the top of the member 15 to. hold In the third form of the invention shown in Figs. 14-16 the rollers, secondary actuator clutch element, and the inner clutch member may be as shown for instance in Fig. 12, but the resilient means urging each roller toward operative position comprises two compression springs I05 engaging the roller and extending into holes I06 formed in a spring holder I01. This holder has a fiat surface I08 to fit against surface 80 and, has also a parti-cylindrical surface I09 having a. radius the same as that of internal surface 84.

The spring holder surfaces I08 and I09 therefore simultaneously fit the surfaces 80 and 84 which form the pocket into which the holder fits and this fit is maintained by the same springs which hold the roller in operative position.

In operation it is found that the secondary element can have its return motion and slide along surface I09 without causing retrograde movement of the driven member. The spring holder may be made of any suitable material, such as'metal, oil impregnated metal such as is used for some hearings, or a resinous plastic material, such as nylon or an acrylic. The roller and spring holder are reversible in their pockets so that either the feeding or return motion of the secondary element can be relied upon to turn the driven member, but as contemplated herein the spring holder and roller with the springs will be used only in such relation as will effect turning 1 of the driven member by a feedingmotion of the. I

By means of 1. secondary element as in the other forms of the invention.

In. all forms of the invention the first and second primary elements may be considered as constituting a. primary clutch. between a driven member, either 40 or 15, andthe worm shaft, and similarly the cylindrical shell-like driving secondary element and that part of the driven member having the flat surface thereon constituting a second secondary clutch element and the rollers may beconsideredas forming asecondary clutch. Inall forms of the invention, the driven member, either 40 or 15, is common to the primary and secondary clutches.

From the foregoing it will be seen that the invention sets forth a simple clutch control means for a loomletoff operating in such manner as to effect smooth uniform feeding movements of the warp beam. The present mechanism includes primary and secondary clutches which perform their feeding operation without moving longitudinally of the worm shaft and in such manner that the slightest amount of motion given by the actuator to the secondary shell clutch element will be communicated to the drivenclutch member to effect angular motion of the worm. The driven member is common to the two clutches and is slidable on the worm shaft to an inoperative position to effect disengagement of the primary clutch elements to enable the worm to be turned by the hand wheel on the worm shaft. In the preferred form the clutch element is so-made that it can be used with letoff mechanisms already in existence, whereas the modified forms are more particularly for use on new looms. The several resilient means in the wedge shaped pockets normally hold the rollers in force transmitting position but they are overpowered by the spring for the actuator rack when the latter has its return idle stroke so that the return motion. of the secondary driving element of the clutch mechanism can effect slight movement'of the rollers to non-force transmitting position. Also, the invention sets forth a drive unit for letofi mechanism which can be readily applied to and removed fromthe worm shaft.

Having now particularly described and ascertained the nature of the invention and in what manner the same is to be performed, what is claimed is:

1. In letoif' mechanism for a 100m having a worm meshing with a worm gear secured to and concentric with a warp beam and having also an actuator which reciprocates to have working and return strokes along a given path in response to the demand for warp feeding incident to loom operation, a shaft transverse of said path to which the worm is secured, a primary clutch element secured to the shaft, a secondary clutch element oscillatable about the axis of the shaft capable of having angular feeding and return motions in a plane normally fixed with respect to said path, a clutch member concentric with and slidable on the shaft from operative to inoperative position and when in inoperative position being rotatable with respect to the shaft, said clutch member being common to the primary and secondary clutch elements and. having a primary clutch part to engage the primary clutch elementwhen the clutch member is in the normal operative position thereof but said part being out of engagement with the primary clutch element when the clutch member is in the inoperative position thereof, rollers intermediate the secondary element and another part of the clutch member effective when the latter is in the operative position thereof to turn the clutch member and cause the first part of the latter to turn the primary clutch element and shaft when the secondary element has a feeding motion but ineifective to turn said clutch member when the secondary element has a return motion, and operative connections between the actuator and secondary element causing the latter to have a feeding motionin said plane when the actuator has a working stroke and causing the secondary element to have a return motion in said plane when the actuator has a return stroke.

2. The letofi' mechanism set forth in claim 1 i wherein said actuator is a rack and said operative connections comprise gear teeth on the secondary the side of said clutch member opposite to the first part of the latter; and a spring surrounds the shaft between the collar and the clutch member and normally urges the latter in' a direction to cause engagement between said primary element and the first part of said clutch member.

a. The letoff mechanism set forth in claim 1 wherein the actuator has the working stroke thereof imparted thereto positively by the loom and a spring effects the return stroke of the actuator.

5. In letoff mechanism for a loom having a worm meshing with a worm gear secured to and concentric with a warp beam, a shaft to which the worm is secured, an actuator which reciprocates transversely of the-shaft along a given path in response to the demand of the loom for warp, a primary clutch element secured to the shaft, a secondary clutch element oscillated about the axis of the shaft by said actuator and having feeding and return angular motions while in the same longitudinal position relative to said shaft incident to loom operation, an intermediate clutch'member concentric with and slidable on the shaft from operative to inoperative positions and when in inoperative position being rotatable on'the shaft, said clutch member including a second primary clutch element to engage the first primary element when the clutchmember is in the operative position thereof, said clutch member including also a second secondary clutchelement within the first secondary clutch element, and rollers operatively interposed between the first and second secondary elements effective when the clutch member is in the op-- erative position thereof to turn the clutch member and'the first andsecond primary clutch elements to turn the shaft and wormwhen the first secondary element has a feeding motion but ineffective to turn the clutch member or move the first secondary element axially of the shaft and transversely of said path when the first secondary element has a return motion.

6. In letoff mechanism for a loom having a warp beam which turns forwardly around the axis thereof to deliver warp, a' worm gear secured to the warp beam, a weighted carrier concentric withthe worm gear mounted to turn relatively to the worm gear, a worm mounted for rotation on the carrier and meshing with the worm gear, an actuator which reciprocates transversely of the axis of the worm along a given path in response to demand of the loom for warp, the carrier tending to turn backwardly and cooperating with the worm and gear to tension the warp, a shell clutch element coaxial with the worm having feeding and return angular motion imparted thereto around the axis of the worm by the actuator without; moving axially of the wormor transversely of said path when the actuator reciprocates during loom operation, a driven clutch member turning in unison with the worm, a rolling force transmitter between the shell and member, and resilient means normally holding the rolling transmitter in driving relation with the shell element and driven member causing the latter to turn in a direction to cause the worm to move the carrier backwardly relative to the worm gear when the shell has a feeding motion, said resilient means yielding to enable the shell when having a return motion to move the rolling transmitter out of driving relation with respect to the shell element and driven member.

7. In letoff mechanism for a loom having a warp beam which turns forwardly to deliver warp, a worm gear secured to and turning with the warp beam, a weighted carrier concentric with the worm gear tending normally to turn backwardly, a worm mounted on the carrier meshing with the worm gear normally cooperating with the latter to enable the carrier to tend to turn the beam backwardly to tension the warp, an actuator which reciprocates transversely of the axis of the worm along a given path in response to demand of the loom for warp, a shell clutch element mounted on the carrier for roe tation about the axis of the worm, said actuator effective during loom operation to oscillate said shell element about said axis and give said shell feeding motions in one direction and return motions in the opposite direction while said shell element remains in the same position longitudinally of the axis of the worm, a driven member within said shell element rotating in unison with said worm, said shell and driven member defining between them wedge shaped pockets which extend from the wide part thereof toward the narrow part thereof in the direction of said feeding motion of the shell element, a force transmitting roller in each pocket parallel to said axis, and resilient means for each roller normally holding the latter in the narrow part of the corresponding pocket and in driving engagement with the shell element and driven member, said shell element when having a feeding motion cooperating with the rollers to turn the driven member and worm in a direction to turn said carrier backwardly relative to said gear, and the carrier due to the tendency thereof to turn backwardly resisting retrograde movement of the driven member and enabling the shell element when having a return movement to move said rollers against the action of said resilient means toward the wide parts of said pockets, the resilient means returning the rollers to their normal positions toward the narrow parts of said pockets upon completion of the return motion of the shell element and without causing movement of the shell element longitudinally of the axis of the worm and transversely of said path.

8. In letoff mechanism for a loom having a warp beam mounted to rotate to supply warp for the weaving process, a worm gear secured to the beam and rotating therewith about the axis thereof, a worm meshing with the worm gear, a reciprocating actuator moved by the loom positively on a working stroke thereof along a given path in one direction from the normal position thereof in response to demand of the loom for warp feeding, a spring effective to give the actuator a return stroke back to the normal position thereof along said path, a driven member connected operatively to and rotating with the worm about the axis thereof, a driving clutch element oscillatable about the driven member, operative connections between the actuator and driving clutch element causing the latter to have an angular feeding motion when the actuator has a working stroke and causing the driving element to have an angular return motion when the actuator has a return stroke, said driving element when having said angular motion remaining in the same position longitudinally of the axis of the worm, said driven member and clutch element being formed to provide between them a plurality of wedge shaped pockets, a force transmitting roller in each pocket, and a resilient means for each pocket normally holding the associated roller in the narrower part of the associated pocket in operative force transmitting position relative to said driving element and clutch member, the driving element on a feeding motion thereof cooperating with said rollers to turn the driven member and worm in a direction to cause the worm to rotate the worm gear and beam, and said spring being effective when causing a return motion of the driving element to enable the latter to move the rollers against the combined action of said resilient means toward the wider ends of said pockets out of force transmitting position relative to the driving element and driven member enabling the driving element to have said return motion thereof without turning said driven member or moving in a direction transverse of said path.

9. In letoff mechanism for a loom operating with an actuator and a worm shaft operatively related to a worm gear on a warp beam, the actuator reciprocating along a path fixed with respect to the shaft in response to demand of the loom for warp, a primary clutch element secured to the shaft in a plane normally fixed with respect to said path, a secondary clutch element caused to oscillate about said shaft by the actuator when the latter reciprocates, a driven clutch member rotatable on the shaft and having a second primary clutch element to engage and form with the first primary element a primary clutch to drive the shaft and having a second secondary clutch element, and force transmitting rollers between the secondary elements which with the latter form a secondary clutch operated by the actuator to operate the primary clutch.

OSCAR V. PAYNE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 465,892 Smith Dec. 29, 1891 811,317 Newton Jan. 30, 1906 1,803,143 Payne Apr. 28, 1931 2,226,232 Payne Dec. 24, 1940 2,269,064 Rideout Jan. 6, 1942 2,282,945 Demarest et a1 May 12, 1942 2,387,215 Fawkes Oct. 16, 1945 2,508,810 Bergstrom May 23, 1950 FOREIGN PATENTS Number Country Date 484,549 Germany Oct. 16, 1929 

